This actually isn’t neccessarily true.
It can be, but depends on the setting itself, and things can be relative. A 9 in a modern setting can just mean a very strong indivdual that might be able to lift up the back half of a car and drag it a bit, etc. Whereas for a superhero, it can mean lifting a semi-truck and tossing it several miles.
Scores in attributes reflect how well you can use what you have. Different characters that can mean different things. It also doesn’t mean you are super smart or have no muscles, again, just how well you use what you’ve got.
A character with 9 Agility but is clumsy (even having the flaw uncoordinated) and often trips or flails while trying to shoot things, and the luck of it causes the bullets to still manage to hit the target, or startle them, etc.